Communication devices, such as two-way radios, often include at least one rotary control knob for controlling such operational features as volume adjustment and channel change. When operating in ruggedized environments, for example public safety environments, a communication device with a good user interface with strong tactile feedback is highly desirable. Users working in public safety environments often carry the device at their side on a belt clip, which requires the user to control knobs and switches without actually looking down at the device. In some applications, the control knobs and switches need to be accessible by users wearing gloves and/or working under noisy and high temperature conditions. A rotary control with a strong user interface is of particular importance in these environmental conditions.
Rotary controls have utilized ball plunger mechanisms in the past to increase torque and improve tactile feedback. However, common off-the-shelf ball plungers utilize springs and materials that can incur decreased performance and deformation after life-cycling and continued on/off usage. Ball plungers can also require lubrication especially in rotary applications which adds potential contamination, complexity, cost, and leads to potential parts degradation.
Additionally, several manufacturing related issues can arise with the use of ball plunger mechanisms including ball captivation problems wherein retention features are inadequate causing that ball to fall out. Unwanted “clicks” may occur when actuating a loose ball and barrel.
Accordingly, there is a need for an improved plunger mechanism that can be applied in switch applications, such as rotary control applications in communication devices.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.